1. Field of the Invention
The present invention relates to cardiac amplifier systems that permit rapid switching between various pairs of patient electrodes. Such an amplifier system can be used in electrocardiographs, heart monitoring systems and other systems that monitor electrical activities of a patient.
2. Description of the Prior Art
Fast switching amplifier systems are known. One such system is disclosed in U.S. Pat. No. 3,477,421 issued to the inventor of the present invention and assigned to the same assignee. The system of the aforesaid U.S. Pat. No. 3,477,421, which is incorporated herein by reference, utilizes a switching transistor to short the input of the amplifier during switching in order to prevent the amplifier from being overdriven by the switching transients and to permit the coupling capacitor to be discharged during the switching operation.
While this system does reduce the amplitude of the switching transients substantially there will be some baseline shift if the switching occurs during a large amplitude portion of the heart wave signal, such as, the peak of the R wave.